1. Field of the Invention
The present invention relates to the preparation and use of certain insoluble polysaccharide derivatives comprising covalently linked gangliosides, and, more especially, relates to the use of such derivatives for the extraction and purification of cholera toxin by affinity chromatography techniques.
2. Cross Reference to Related Applications
1. Serial No. 475,305, filed May 31, 1974, now U.S. Pat. No. 3,947,352; hereby expressly incorporated by reference and relied upon.
2. Serial No. 475,314, filed May 31, 1974, now abandoned, and copending continuing application, Ser. No. 713,108, filed Aug. 10, 1976; hereby expressly incorporated by reference and relied upon.
3. Description of the Prior Art
It has recently been demonstrated that the enterotoxin from Vibrio cholerae, which is responsible for the gastrointestinal manifestations of clincial cholera, binds very strongly to gangliosides and less strongly to certain glycoproteins such as fetuin and thyroglobulin. Cuatrecasas, Biochemistry, 12, 3547 (1973a); Cuatrecasas, Biochemistry, 12, 3558 (1973b). Gangliosides block the biological effects of cholera toxin on isolated fat cells [Cuatrecasas, 1973a, supra; Cuatrecasas, 1973b, supra; van Heyningen et al, J. Infec. Dis., 124, 415 (1971)] and on the small intestine [van Heyningen et al, supra; Pierce, J. Exp. Med., 137, 1009 (1973); Holmgren et al, Scand. J. Infec. Dis., 5, 77 (1973)], and they prevent the binding of .sup.125 I-labeled cholera toxin to specific receptors on the cell membranes of various tissues, such as adipose tissue, liver erythrocytes, and intestinal epithelial cells; Cuatrecasas, 1973a, b, supra. There is considerable evidence indicating that gangliosides, and specifically G.sub.M1 gangliosides, are the natural membrane receptors with which cholera toxin specifically interacts to elicit its biological effects in tissues; Cuatrecasas, 1973a, b, supra.